A wireless network system using the millimeter wave frequency band (e.g. 60 GHz) is well adapted to the transmission of uncompressed High Definition (HD) video or image data. One of the most advantageous characteristics of a wireless network using the 60 GHz frequency band is a large available bandwidth. This large bandwidth allows very high data rate transmission (more than 3 Gbps at the application level).
However, a main drawback of a wireless network using the millimeter wave frequency band such as the 60 GHz frequency band is its sensitivity to the shadowing phenomenon. Static or moving obstacles such as furniture, objects and human beings can cut or disturb the communication path and cause transmission errors.
Several solutions exist to handle such wireless data transmission perturbations.
For example, French Patent application No FR2924288A1 discloses a Chase Erasure Decoder to be used in a wireless mesh network. According to this document, a receiver node receives two copies of a same original Reed Solomon (RS) codeword (consisting of several symbols) transmitted from two different transmitter nodes (i.e. from two different independent radio communication paths).
After having received the two copies of a same RS codeword, the receiver node compares, symbol per symbol, the two different copies of the RS codeword to construct a resulting RS codeword. If the symbols of the two copies of the RS codeword are the same, the symbol value is duplicated in the resulting RS codeword. On the contrary, if the symbols of the two copies are different, the symbol is identified as an erasure in the resulting RS codeword.
In a following step, the number of erasures identified within the resulting RS codeword is compared to the decoding capacity of the RS decoder. If the number of erasures is equal to or is less than the RS decoder capacity, the resulting RS codeword is sent directly to the RS decoder to be decoded. On the contrary, if the number of erasures is greater than the capacity of the RS decoder, the resulting codeword cannot be sent directly to the RS decoder. In that case, the first symbols identified as erasures in the resulting RS codeword are replaced by the corresponding symbols of one of the received copies of the RS codeword.
The modified resulting RS codeword is sent to the RS decoder to be decoded. If the output of the RS decoder is not correct, a new iteration is done by replacing another set of symbols identified as erasures in the resulting RS codeword by the corresponding symbols of one of the received copies of the RS codeword. Iterations are stopped when the RS decoder output is correct or when all possible symbol replacements have been tested.
As another example, U.S. Patent Application Publication No. US2010/026900 discloses a method for a multi-reception wireless system. According to this document, the receiver that receives several copies of the same packet sent by a source, representing the original data to be retrieved, splits each received copy into multiple sub-packets. These sub-packets are then combined to reconstruct a packet that is subject to a CRC computation. If the CRC check is positive, the reconstructed packet is presented to the upper layer of the receiver. Such a method provides good performance when at least one of the received copies has a low bit error rate.
Another decoding technique that can be used in a multi-reception wireless system is based on the known majority or quorum decision scheme. According to the majority decision scheme, the output of the decoder corresponds to the data that are the most represented at the input of the decoder. Such a decoding technique is efficient if the considered radio communication paths have similar BER.